Portable power tool



A118'. 22, 1950 K. J. SAYRE 2,519,936

PORTABLE POWER TooL Filed June 2o, 194e 2 sheets-sheet 1 Aug. 22, 1950K. J. sAYRE PORTABLE POWER TOOL 2 Sheets-Sheet 2 Filed June 20, 1946`Patented ug. 22, 1950 UITED STATES ,ATENT OFFICE 4 Claims.

This invention relates to portable power tools, and more particularly tola portable .tool in geombination with an internal combustion `engineadapted to `be .supported upon the back of the user. Preferably, theinternal combustion en- 5 gine will be of the air-cooled, two-strokecycle tion oi the invention is thereby intended :and that type, quitesimilar to the `small outboard marine various `changes and alterationsare 4con-templated engines no'win comm-on use. such `as would ordinarilyoccur to .one skilled in It is a principal object .of the presentinvention the art to which the invention relates. to provide a portabletool .of the type described. Referring to Figures l and the presentincomprising a supporting structure adapted to be vention comprises vaninternal combustion engine worn upon the back of the user, an internalcomdesignated generally by the reference character bustion enginesupported upon said structure, and lil connected by means of a nextdrive shaft a tool connected to said engine through a exible with a tooll l supported within a housing l2, drive shaft, the supporting structurecomprising which housing is attached to .a rhandle lladapted an airintake passage Vthrough which cooling air `to be supported by the hands.of the user. The for the engine is drawn, thereby insulating the engineil? is supported on the back or the user back yof the user from thevheat of the engine. throng-h t e medium of a supporting structure Afurther object is the provision of a portable Vis. which may suitablysecured upon back tool of the type described including a handle of theuser by means of straps i5. The support.- structure for supporting thetool in use, said ing structure le is `Vmate hollow zcomprises handlestructure including 'hand grips and engine the air intake passage for.the cooling air supply control means connected to the engine by lexibleto theengine means such as Bowden wires 'or the like. The engi-ne -lilis preferably of the twofstroke A further object is the provision of aportable `cycle type and is quite similar to small outboard tool of thetype described in which the flexible marine motors now in common use.Its Single drive shaft is connected `to the engine through cylinder it'is provided with cooling fins in .the an adjustable slip clutch, wherebydamage to the usual manner, and the flywheel ll is vprovided tool and/orthe engine is prevented in the case of with peripheral vanes l ii. Ahollow structure lil the tool encountering an obstacle or beingoverconnects the llywheel ll with the space surrcundloaded, ing theupper portion of tho cylinder i6 and serves A further object is theprovision of a portable as a passage for the cooling air which forcedtool of the type described in which the direction downwardly by thevaries A3 as the flywheel roof airow through the supporting structuremay tates. be reversed, whereby the supporting structure Air iS Suppliedt0 the VSIISS E3 'fhl'llgh the may be warmed with the heat of the enginedursupporting structure M which may be of alumiing cold weather. num orother light metal, or of other suitable Other and further Objectsfeatures and :admaterial. The SllllCllle Hl iS relatively Wide vantageswill be apparent from the description and shallow, and is preferablyshaped approxiwhich follows, read in connection with the acmately to theconformation of the back of a percompanying drawings in which son, sothat it may be comfortably worn by the Figure l is an elevational viewof a tool conuser of the tool. The engine lil is supported structed inaccordance with the invention, with upon the structure le through themedium of a the power source attached to the back 'of the bracket or arm2G which may be riveted or otheruser; wise secured to the structure le.En the illus- Figure 2 illustrates the 46001 0f Figure l in side tratedembodiment, the rotation of the iiywheel elevation, With the COOlng airpassages 0i the ll will cause cooling air to be drawn upwardly internalCQmbuStOIl engine Shown partly in verthrough the structure lll andforced downwardly CalSeCOn; past the cylinder I6, the passage of thecooling Figure 3 is a top plan View of the power Source 50 air throughthe structure lil serving to insulate illustrated in Figures l andZ; theback of the user from the heat generated by Figure 4 is a bottom planView oi one type of the engine. In cold weather, a substitute fan tooladapted to be operated in Iaccordance with portion having reverselyinclined vanes may be the invention, together with its housing; andapplied to the ywheel I7, whereby heated air Figure 5 is a plan view ofthe cutting tool of will be forced downwardly through the structureFigure 4.

In order to facilitate ,en understanding of the invention, reference ismade to the embodiments thereof shown in the accompanying drawing@ and.detailed descriptive language is employed. 1t will nevertheless beunderstood that ,no limita The engine is provided with a carburetor 2|including a fuel Valve operated through the medium of an arm 22 which isconnected by means of a link 23 to a bell crank lever 24. The latter isdisposed exteriorly of the clutch and governor housing 25 and is securedupon a shaft 26 which extends into the housing 25. A yball governor (notshown) of any suitable type is enclosed within the housing 25, andserves to control the fuel valve through the medium of the shaft 26,lever 24, link 23, and arm 22. The fuel valve may also be manuallycontrolled through means to be described. The housing 25 also containsan adjustable spring pressed clutch (not shown) connecting thecrankshaft of the engine With a heavy duty flexible shaft containedwithin the flexible housing 21. flexible drive shaft is secured to thecutting tool Il as seen in Figure 2.

The handle I3 upon which the tool housing I2 is supported is generallysimilar to a scythe handle and is provided with two spaced hand grips 29and for manipulation of the tool. A fuel control lever 3| is associatedwith the hand grip 30 and is connected by means of a Bowden Wire 32 withthe bell crank lever 2d, thus providing manual control means for theluel valve. A clutch control lever 33 is associated with' the handgrip29 and is connected by means of a Bowden wire 34 with a lever 35secured upon a shaft 3G which extends into the housing 25 and operatesthe clutch.

The tool illustrated in the present embodiment comprises a serrated discadapd for cutting weeds, and the housing or guard l2 is provided withV-shaped notches or serrations as seen in Figure 4, to admit the weedstems to contact with the teeth of the cutter. Obviously, other toolsmay be substituted for the cutter Il, as for example a saw blade, a wirebrush, or the like, in which case modlication of the housing I2 would berequired, depending upon the type of work to be performed. Modificationof the shape of the handle I3 would also depend upon the type of tool tobe driven and the nature of the work to be performed.

Having thus described the invention, what is The lower end 28 of theclaimed as new and desired to be secured by Letters Patent is:

1. In a portable tool including an internal combustion engine, asupporting structure comprising a hollow member open at two points oneof which is adjacent the combustion area of said engine and the other ofwhich is removed therefrom, means supporting said engine on saidstructure, and means for passing air through said structure.

2. In a portable tool including an internal combustion engine, asupporting structure comprising a hollow member open at two points oneof which is adjacent the combustion area of said engine and the other ofwhich is removed therefrom, means supporting said engine on saidstructure, and means operated by said engine for passing air throughsaid structure.

3. A device according to claim 1, said supporting structure consistingin a relatively wide and shallow conduit shaped approximately to t theback of a person.

4. For an air-cooled internal combustion engine, a supporting structurecomprising a relatively Wide and shallow conduit, said conduit beingcurved approximately to fit the back of a vperson and having an orificeadjacent the combustion area of said engine, and means for supportingsaid engine on said structure.

KENNETH J. SAYRE.

REFERENCES CITED The following references are of record in the le ofthis patent:

UNITED STATES PATENTS Number Name Date 1,370,768 Sperling Mar. 8, 19211,981,076 Sells Nov. 20, 1934 2,119,962 Raleigh June 7, 1938 2,326,335Dehn Aug. 10, 1943 2,434,089 Allen Jan. 6, 1948 FOREIGN PATENTS NumberCountry Date 138,928 Austria Oct. 10, 1934

